Sen. Susan Collins is flexing her bipartisan credentials in her reelection race in Maine, rolling out a new television touting her record of working across party lines.

The ad plays off the 2019 “Bipartisan Index” scorecard the Lugar Center and the McCourt School of Public Policy at Georgetown University released this week that showed the Republican has “extended her unprecedented run as the most bipartisan Senator.”

“In a world where everything is changing, some things stay the same,” the narrator says in the new Collins ad. “For the seventh year in a row, Susan Collins has been named the most bipartisan U.S. senator.”

“No matter what party is in the White House or in control of Congress, Susan stays the same — never missing a single vote,” the narrator says.

Ms. Collins is locked in a tight race against Sara Gideon, speaker of the Maine House.

Democrats see the contest as one of the best chances to flip a seat in the Senate and as a must-win if they hope to flip control of the chamber.

Challenging Ms. Collins‘ bipartisan image, Ms. Gideon has cast her as a closet partisan, arguing the incumbent falls into line with President Trump and Senate Majority Leader Mitch McConnell when it matters most.